Question

A sphere of mass 25 Kg is moving at a speed of 1.5 m/s undergoes collision with another sphere of mass 50 Kg moving at 3m/s in the same direction, find the velocity of 25 Kg mass in m/s after collision when the collision is elastic.

(a) 2.5

(b) 2.00

(c) 3.5

(d) 6.75

This question was posed to me in an internship interview.

My query is from Loss of Kinetic Energy During Elastic Impact in section Kinematics & Kinetics of Motion of Machine Kinematics

Answer 1

Right option is (c) 3.5

The best I can explain: Velocity during elastic collision is given by

m1u1 + m2u2/(m1+ m2) = v

substituting the values we get

V = 2.5 m/s

v2 = 2V – u2

v2 = 3.5 m/s